I had the same problem in thinking that if you had A-levels you wouldn't be able to do Access to HE courses as you already have a full level 3 qualification. I completed my A-levels in English Language, Sociology and Psychology in 2009 and since have been working as I felt studying English at university wasn't my thing anymore.
Since then I have been researching Access to Medicine/Dentistry courses available in FE institutions in London, my interest in such a course comes from having the oppourtunity to work in the NHS in a clerical position whilst being able to observe the clinical staff throughout my post, I have therefore applied and gained a 12 month placement as a trainee dental nurse at UCLH in feb 2011
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I hope to apply for the Access to Medicine course after this at either City and Islington College or Lambeth College both based in London, the admissions lady did emphasise that mature applicants with A-levels stand a better chance of gaining entry as their application stands out as the course is fairly demanding and only the best suited applicants will be allowed to even apply for dentistry or medicine.
Oh well, see what the future holds